A bisection-function technique to characterize heat transport in high-power GaN-based light-emitting-diodes package

The transient response of the junction temperature of packaged high-power GaN-based light-emitting diodes (LEDs) is numerically simulated. We found the heat transport in LEDs involves two evident processes and can be characterized by a bisection function. One process involves heat transfer from a LED chip to its slug submount, whereas the other involves the heat transfer from the slug submount to the ambient through the heat sink. The thermal time constant of the two processes are identifiable. The time constant of the first process is in millisecond order of magnitude, whereas that of the other process is in hundred-second order of magnitude. The thermal resistance in the two processes can be obtained by analyzing the transient response curve of the junction temperature.